Environmental sirens in Delta are screaming

The Delta's
open-water fish populations are mysteriously collapsing in a crisis that
threatens to unravel the food web of the West Coast's largest estuary.

Delta smelt, already a threatened species, fell last fall to the lowest
level ever measured. Same with young striped bass, according to the results of
annual surveys by the California Department of Fish and Game

And the key
food source for small fish in the Delta, tiny organisms called copepods, are
plummeting as well, with numbers of a key species falling to extremely low
levels.

The rapid, multispecies decline could trigger measures that
might affect water quality and supply from Contra Costa County to Southern
California.

Scientists say information in a number of different surveys
of the Delta and Suisun Marsh revealed an ongoing, sweeping population crash
that could not be explained by drought or any other easily identifiable cause.

Scientists familiar with the decline expressed varying degrees of
concern, but some said they are alarmed.

Asked if the latest information
reflected "a widespread ecological collapse" in the Delta, a fisheries biologist
at the U.S. Environmental Protection Agency said, "I'm
not much of an alarmist, but I'm starting to look
at it that way. I'm starting to look at it as the
sky is falling."

The EPA biologist, Bruce Herbold, said it was the sudden
decline of threadfin shad, a previously common baitfish, that caught his
attention.

"To have it going from really abundant to scarce, it's
scary," Herbold said. "Something is really, really
wrong. It is not just the sensitive fish. The cockroaches
are dying off."

The ongoing crisis
threatens not only the Delta's food web, it also threatens to disrupt two of the
state's largest water delivery systems.

Those water systems, which
together deliver trillions of gallons of water each year from the Delta to the
Central Valley and Southern California, are more likely to be curtailed when
concerns deepen over fisheries.

If that happens, and large water users
south of the Delta begin taking more water at other times of the year, it can
worsen the water quality in the Contra Costa Water District.

The crash
is especially surprising because it comes 10 years into an ambitious and
expensive program called CalFed that was designed to prevent this kind of
crisis.

"Despite all the work that has been done, we're not making
progress," said Tina Swanson, a senior scientist at the Bay Institute, an
environmental group. "We are now seeing a decline,
and that is disturbing."

For Delta smelt, a year-round Delta resident whose status has major
implications for water management, the slide is particularly dramatic.

In late 2002, the tiny fish ended a five-year cycle in which it met all
the criteria to be considered a recovered species no longer in need of the
protection of the Endangered Species Act. As a result, water users sued to
prevent regulators from imposing water restrictions to protect the smelt, but so
far that lawsuit has not been successful.

Some scientists at the time
said the apparent recovery of Delta smelt was probably due to a string of wet
years, while others noted that even though it had met criteria for the five-year
period, its numbers were already beginning to taper off.

Now, the Delta
smelt population is at its lowest level ever.

Herbold said one of two
things has happened: either the Delta has degraded
so badly that conditions have passed a "pivot point" and
are in a general collapse, or some unknown factor
has changed.

The suspected culprits that could have quietly changed the
Delta environment over the last three years or so fall into three broad
categories, and scientists say it is most likely that a combination of factors
is causing the problems:

€ Toxins. Pesticides from throughout the
Central Valley drain into the Delta, and herbicides
are sprayed directly into the Delta to kill weedy plants.
Also, as regulators are phasing out one class of pesticides,
another called pyrethroids that is especially toxic
to fish is being used more commonly throughout California.

€ Invasive species. Numerous
non-native plants and animals have been introduced
into the Delta from various sources -- including ship
ballast and dumped aquariums -- dramatically changing
the Delta environment.

€ Giant pumps. Not only has Delta pumping
increased during the last two years to near record
highs, the timing of the greatest pumping has shifted
from spring to later in the year. The amount or timing
of pumping might be contributing to the problem by
altering the flow of water in the Delta and killing
organisms that are drawn into the pumps.

The spring runoff has been strong this year, and in theory that should
lead to at least some improvement in fish surveys later this year.

"If
it doesn't, then we need to be really, really concerned," said Swanson. "That
would be a sign that the system is no longer capable
of responding to improved environmental conditions."

The decline in fish species was revealed in
the results of annual surveys biologists do for "pelagic," or
open water, fish and zooplankton.

Scientists say the decline appears to have begun about
three years ago, although the exact date is hard to pinpoint; it may have
started earlier but gone undetected because wet years can mask stresses on fish
populations.

The slide has affected all of the dominant pelagic fish in
the Delta, including Delta smelt, longfin smelt, threadfin shad and young
striped bass, said Randall Baxter, a senior fisheries biologist at the state
fish and game department.

Paradoxically, adult striped bass populations
remain healthy despite what has been a longer-term decline among the young
striped bass.

In addition, copepods have fallen to worrisome levels. One
of the most important pelagic fish food sources, a tiny organism called
pseudodiaptomus forbesi, has fallen dramatically.

"It's pretty scary,"
Baxter said. "The other copepods that we're aware
of are kind of in the same boat. They're all looking
pretty bad. ... What we're seeing is a portion of
the food web is collapsing."

Baxter cautioned that so far, the problems
appear confined to open water species. He said he hopes that copepods are still
abundant in pockets around the Delta where scientists have not collected
samples.

Meanwhile, scientists are looking to see if similar problems
are developing among shore fish, bottom fish or migratory fish.

So far,
they have found no clear evidence that those categories are affected. Baxter
said it is too early to say for sure, but survey records for bottom, or benthic,
fish do not appear to show a problem.

On the other hand, recent surveys
of juvenile salmon migrating down the San Joaquin River showed a sharp drop in
the number of successful migrations during the last two years.

"Perhaps
there's a problem (causing the salmon to die), but it's probably too early to
say for sure," said Pat Brandes, a fisheries biologist
at the U.S. Fish and Wildlife Service.

Scientists have begun meeting and planning a summer of
intensive work in the Delta and say that by fall they should be able to
eliminate several culprits and begin sorting out exactly what's going on.

"We're going to put everything on the table, from toxics to water
operations to (invasive) species to even toxic algae," said Kevin Fleming, a
state fish and game fisheries biologist. "Everyone
is pretty clear in that there's something going on
out there. The only question is what it is and what
is going to be done about it."

The decline of copepods is obviously
important, since it is a key food source for all of the pelagic fish that are in
decline.

But no one knows what is killing the copepods, and whether
whatever it is that is killing those organisms is also killing small fish.

Pesticide use patterns offer one intriguing possibility, said Herbold,
the EPA biologist.

In recent years, one class of pesticides,
organophosphates, is being phased out and in many cases replaced with
pyrethroids, one of the least toxic insecticides to mammals, according to the
National Pesticide Telecommunications Network.

But pyrethroids have a
significant drawback.

"Pyrethroids are much more toxic to fish," said
Kathryn Kuivila, a research chemist who studies pesticides in California surface
water for the U.S. Geological Survey. "Some of the
newer ones are ... more toxic (to fish) than the
ones that were used in the 1990s."

Invasive species,
meanwhile, have wreaked havoc on the Delta ecosystem in a whole host of ways.
Exotic clams now consume massive amounts of phytoplankton that are important
food sources, while aquarium plants have grown so thick in places they slow down
water circulation.

The pumps at Byron and Tracy that move Delta water to
the Central Valley and Southern California are a highly visible suspected cause.

In the last two years, those pumps moved water at the second and third
highest rates ever. Only in 2000 was more water pumped out of the Delta.

And to protect fish like Delta smelt, much of that pumping has been
shifted to the summer from the spring, when smelt tend to congregate in areas
affected by the pumps.

"That (pumping) comes to the top of the list for
a lot of people," said Herbold.